Aircraft: C172
Phase of flight: Parked
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance

Approximately 2.5 weeks ago; I was contracted to complete a 100 hour inspection by a personal friend who owns a local flight school. The owner has had a difficult time finding mechanics to work on his equipment. The flight school had previously employed some mechanics that appeared to not fully inspect/maintain the school's aircraft properly. Prior to my offering to help the owner; one of his aircraft had suffered a flight control failure/jam which had attracted the attention of the FAA. I agreed to help my friend (owner of the school) in order to help him keep his aircraft flying by fixing them.I had previously performed a few 100 hour inspections prior to this on the owner's aircraft. During these previous inspections; I discovered quite a few discrepancies that I corrected/repaired and documented in the logs. This would be the second time I performed a 100 hour on this aircraft. I work with an individual who is not a certified mechanic; but has previously been certified in the past. This individual works under my supervision and does not inspect any part of the aircraft; he only corrects discrepancies (which I then inspect). During this inspection; I discovered and corrected a few minor discrepancies; but at a level nowhere near the number and severity discovered during the previous inspection. I signed off the aircraft and returned it to service. The aircraft has been flying regularly for the past 2 weeks. Today I discovered that the FAA inspected the aircraft and tagged it. The inspectors provided a list which contained: door hinge pins; signs of damage at rudder; possibly 1 incorrect flap installed; cowling Cam-Loc too long; [and] 1 rudder pedal appears worn.While I have not been contacted by the FAA; I don't believe I could have missed those items at all during both inspections. If in fact I did miss them; I can only contribute that to feeling rushed. In a perfect world; a mechanic would have an infinite amount of time to inspect/repair an aircraft in an air-conditioned hangar. However; this isn't always the case. Feeling pressured to finish the plane due to lost revenue combined with 100+ degree heat could possibly lead to making mistakes. The mechanic perhaps inspects the smaller items - but may not inspect them thoroughly. While I am not admitting I didn't inspect the items above; it may be possible I didn't look at them long enough. Even-though the owner is a personal friend; I spoke with him about the importance of downing the aircraft to fix all the items. This can sometimes be a major issue at a small flight school. A mechanic needs time to accurately and correctly inspect/repair an aircraft.I also spoke with the owner about the importance of documenting ALL maintenance. I noticed after I inspected the aircraft other mechanics had worked on it. I am unsure if any of their work was documented. It is important to do this because; (for example); another mechanic removes the cowl to fix a starter; loses a cowl fastener; and puts an incorrect one in without documenting it [and] then something happens. It may still be seen as the fault of the last mechanic who documented removing the cowl in the logbooks.I will remember that the importance of taking your time while performing maintenance and inspections; and documenting all maintenance in the logs will ensure pilots and the public are provided with a safe aircraft. Technician reported the FAA found irregularities after the 100 hour inspection on a Cessna 172 was completed.